


The Flesh is a Machine

by mostlyharmless



Category: Big Hero 6 (2014)
Genre: Aged-Up Character(s), Aged-Up Hiro, Anal Fingering, Anal Sex, Body Modification, Domestic Fluff, Established Relationship, Lube, M/M, Other, Robot Kink, Robot Sex, Robot/Human Relationships, Size Difference, Size Kink, Vibrators
Language: English
Status: Completed
Published: 2015-01-28
Updated: 2015-01-28
Packaged: 2018-03-09 23:53:08
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,516
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3268940
Author URL: https://archiveofourown.org/users/mostlyharmless/pseuds/mostlyharmless
Summary: <blockquote class="userstuff">
              <p>Hiro Hamada is twenty years old and has a pretty sweet life - interesting robotics gig, cool apartment, cute boyfriend. He has to admit that it's not exactly normal how those things overlap, but whatever. He and Baymax more than make things work. (Warning for utter smut and robotics terminology of dubious accuracy.)</p>
            </blockquote>





	The Flesh is a Machine

**Author's Note:**

  * For [VoodooRadio](https://archiveofourown.org/users/VoodooRadio/gifts).
  * Translation into 中文 available: [The Flesh is a Machine 色即是白](https://archiveofourown.org/works/3549245) by [Glacier](https://archiveofourown.org/users/Glacier/pseuds/Glacier)



> Happy birthday Mina o3o I tried...!!!
> 
> Hiro is 20 years old in this story.

"Welcome home, Hiro," said the wall, as Hiro dumped his bag on the wooden part of the floor and kicked his shoes into a corner of the little entrance recess.

"Thanks. Did you start up the rice cooker when I texted you?"

"Of course," said the wall. "It should be ready soon."

Hiro padded into the kitchen, the lights turning on as he went.

"Thanks," he added. He got weird looks at the university whenever he forgot where he was and thanked automatic doors and lights, but honestly? He'd rather mess up like that than ever forget to treat Baymax like a sentient being.

Last year, when his various licensed patents started raking in the big bucks, he'd finally got a brand spanking new apartment of his own. Not because he didn't love Aunt Cass, but, well. He was more than ready to spread his wings a little more.

The apartment, like most new places these days, was already fully wired for the installation of a home AI. Hiro had browsed the brochure the agent had given him, looking at the options and pricing, before deciding it'd be way more fun to write his own.

But halfway through that project, he'd realised Baymax didn't seem all that pumped about it. He was weirdly quiet, and then started asking some pointed questions that made Hiro laugh and ask him, what, you thinking of a career as a housebot?

Baymax had just said, candidly, that he was the one charged with Hiro's personal care, and he didn't see why Hiro needed anyone else.

Hiro had flushed stupidly and had to go squash Baymax' cheeks and tell him he was silly.

After all, Hiro had already built him several new platforms since the first one he'd made himself six years ago, many of them deviating significantly from Baymax' original balloon-mallow design, often due to Baymax' own suggestions.

So, being a house probably wasn't all that weird.

He had backed up the current data in Baymax' cloud, created a new restore point for the core files that had originally come from the old green data card, and, after some hardcore programming (and a kinda painful debugging period which nearly saw Baymax burn the place down because Hiro forgot to close a bracket in the _if(shit is burning) {abort();}_ command in the oven subroutine), Baymax had an even larger, even more expressionless option with which to incarnate himself in down in meatspace. It came complete with an autopilot-type virtual intelligence that could take over the important functions when he was online somewhere else.

Hiro grabbed a random leftovers container out of the fridge and tossed it into the microwave.

There was a muffled beep from the closet up in the loft above the TV area, and at the same time, a green light on the wall turned yellow. There was a whir and some shuffling, then Baymax was squeaking down the stairs in his oldest (well, the oldest still in this dimension) platform.

"Should I turn the rice?" Baymax asked, putting on an apron, and the domesticity of it all made Hiro all weird and warm inside.

They had the TV on while Hiro ate, leaning back in Baymax' lap on the sofa, but Hiro wasn't really watching it. He told Baymax what he'd been up to that day, updated him on where he was up to on his latest project.

"Perhaps I will leave the VI system in charge tomorrow, and come in with you. I have not seen everyone in a while."

Of the five of them, only Gogo had left to do something different with her degree, although they saw her (saved the world with her) often. The others, now in their thirties, were still content with the academic life.

Hiro had kinda toyed with the idea of his own robotics startup, but had quickly realised that it would mean a lot more time doing boring paperwork and managing people and a lot less time actually playing with robots. So, for now he was content to sell his tech to people who were already experts in corporate BS.

"It's up to you," said Hiro. "I hope you don't pick a body that's too bulky, though. You know how Wasabi gets when you bump his stuff."

"The black model is rather sleek," said Baymax, and Hiro felt himself go pink. Of all the ways in which Baymax had evolved, his ability to tease was still the most surprising.

"You wanna wear the black model out in public, you better be prepared to go it alone."

"That seems counterproductive to the primary function of that model. I recommend you stay close to me whenever I am in it," and goddamn, Hiro was not going to let himself start cursing Tadashi's fucking enabler programming now, because his dead brother was the last thing he wanted to think about when his robot boyfriend was talking about putting on his sextoy model.

"Not sure I remember the primary function," said Hiro, trying not to cringe at his own flirting, because nobody whose entire romantic experience was with a robot should be expected to be very good, and said robot didn't care anyway. "Why don't you remind me?"

Baymax got up without a word, sending Hiro sliding onto the couch, and toddled over to a charging dock in the corner. As his white plastic eyelids slid down over black glass, there was another beep from upstairs.

This time, Hiro went up there.

 

* * *

 

Baymax was waiting for him on the bed. Hiro shuffled over, suddenly shy. He focused on the familiar face he'd left in the design.

The black model was large and imposing, matte black and firm. This Baymax was solid, polymer moulding around his skeleton instead of air, but when Hiro reached out a hand and stroked the silicon, he felt the thick layer of elastomer underneath it squish pleasingly under the pressure of his fingers.

He crawled up into Baymax' lap, let the robot rearrange his legs with fingers just as soft and strong, and shivered as he felt the huge hands on his hips pull him flush against the seamless phallus jutting up there.

That was the main reason he got shy around this particular platform, despite the fact that he had built it himself - when he saw that massive, silicon coated black cock, all he could think of was how it felt splitting him open, and.

He whined, mouthing at Baymax' silky silicon shoulder.

"Should I start the vibrations?"

Hiro nodded, not lifting his face.

"Understood. I will begin with pattern one."

Baymax knew him well.

The fingers on his hips started to vibrate, as did the cock between Hiro's legs. He gasped as one big palm cupped his ass and pushed him firmly against it. The vibrations were gentle, but rumbled deeply through his body, muted as it was through his pants. Then fingers slid up under his shirt, drew buzzing lines up his stomach, ribs, pressed into his nipples. He gasped again, this time more voice than breath.

"Come on already," he bit out, when he couldn't stop his hips from grinding forward.

"I suggest you undress, then," said Baymax, letting him go, and he skinned out of his clothes as fast as he could before those big hands grabbed him again, pushed him down on his hands and knees.

"Please, please," he said, and groaned as he felt lubrication squirt down the crack of his ass. Baymax massaged it in with those maddeningly soft fingers, pushing at his hole. "Yeah, there, do it," Hiro panted.

Baymax didn't really need instruction, though. It wasn't long before Hiro was squirming on his fingers, gasping as the vibration pattern switched over to something that flared high every time Baymax pushed them in just so. The other hand, silky and skin-warmed, skimmed over his hip and started to press his dick up against his stomach, pulsing in time with his ass.

He felt the heavy warm current in his guts suddenly spark.

"Hah--stop," he managed, and Baymax did. "I'm gonna come if you keep doing that. Just, you know."

"Would you like to come with me inside you?" Baymax asked, and while looking at the monster dick Hiro had built was a little too embarrassing to deal with, Baymax himself was nearly worse. But worse in the good way.

"Read my mind, buddy," he said, panting. He wiped his sweaty face against the sheets.

Baymax let out a melodic hum, something Hiro had programmed him to do when his social algorithm was telling him he was supposed to respond, but he had nothing to say. It made him a better healthcare assistant…

The huge fingers were now focusing on stretching him, his rim being tugged and pulled as they pushed in and out. He felt liquid squirt deep inside his ass, and he squeezed down with a small cry.

Baymax stilled questioningly.

"I'm not, no," Hiro panted, and Baymax must have scanned his body to corroborate that data, because after a slight pause he continued.

It was nearly relaxing, the mechanical, even strokes that were coaxing Hiro open, but they began to feel nearly teasing, not nearly enough. Pulses of arousal were running to all his extremities, his fingers, toes, his hanging dick.

He pulled away, Baymax' hands shifting on his body as Hiro flopped over onto his back to breathe.

"I think it'd be okay now…"

"How would you like to proceed?"

"...Sit up here, yeah like that, just lie back against the--yeah." He crawled into Baymax' lap again, feeling empty and wet. "I wanna ride you."

"Take your time," said Baymax, and Hiro kissed his face.

Despite how loose he was, he really had built this thing to destroy. He gripped it with one hand, Baymax' shoulder with the other, and pushed the tip of it against his asshole. The feel of the blunt edge of it sliding against his hypersensitive rim had him tensing up.

Baymax' fingers came up to tug his lip away from his teeth.

"You will cause damage," he admonished, and Hiro turned his head and caught the fingers in his mouth instead. They tasted like musky, salty fluids, and when that was all licked up, his tongue dragged against wet silicon, tasting something faintly rubbery and his own spit.

The other hand was pressing a finger into his ass again, pushing deep and up and then releasing more lubrication, enough this time that Hiro felt it come sliding out of his ass in globs, even as he tried to tighten up to keep it inside. He moaned as the finger fucked into him, the repeating motion exact and measured like a metronome, and as it withdrew, this time, when he pressed the big rounded head of Baymax' cock against his hole, it slid easily in through all the slick.

Hiro could barely keep his eyes open as he pushed himself down, feeling it spread him wide open deep inside. He stopped halfway down it, aching and hot.

"G-give me a hand," he managed, and Baymax' hands gripped his hips - the saliva on one leaving cold-air trails over the bone there - and helped him move. He looked down, arousal fuelled by the way his own skin dimpled where strong fingers gripped his thighs.

It was like something was unwinding in his hips. He screwed himself in tight circles, looking for the angle that would help the ache, and when he found it he sucked in a breath and started moving faster, bouncing himself, hips tilted rigidly. He was feeling it in his fingers and toes again...

Baymax stroked his back, tugged a little at his hair.

"Breathe," he said, and Hiro sucked in a breath, head swimming, realising he had been holding it in concentration. Baymax finally dropped that hand between them, into Hiro's lap, and started to stroke his cock.

He tried to let go, arousal running through him, glowing hotter with each breath he drew. The hands on his hips were barely cupping him, letting him pant and fuck himself down. He could see the trails of sweat and fluids he was leaving all over the matte black skin.

"P-pattern four… please…," he groaned, trying to angle his hips right, and then Baymax' cock came alive inside him, vibrating in intense, deep pulses right where he needed it--

Orgasm swept through him, a surge of white pleasure that sparked through his entire body. He felt himself clench down again and again on the huge thick intrusion inside him, and it was nearly like coming a second time.

Baymax' whole front was a mess. Hiro was a mess. He pulled himself off, tugged at Baymax until he shifted his heavy body to lie beside him.

"Let me get you," he said, trying to catch his breath.

"Please," said Baymax, and his voice was just as light as ever, but Hiro knew he had to be ready to get off already.

He found the special device they used where it had fallen down between the wall and the mattress, and held it to the sensor between Baymax' legs, at the base of the phallus. Hiro's hands were slippery and sticky, but he managed to hold the button long enough to turn on the magnetic field he had designed to simulate the heavy internal pressure of arousal.

"I would like to be kissed," said Baymax, and Hiro wedged the device securely and climbed up him with a big grin.

"That I can do."

"There probably is not much you cannot," said Baymax, and Hiro had to kiss his face. Not that that stopped his audio unit from working. "You are amazing, Hiro."

"Shut up," said Hiro, feeling kinda hot again. He was leaving saliva on Baymax' face, and his lips felt swollen. "You're the amazing one."

He licked Baymax, pushed his tongue against the thick elastomer, feeling the way it yielded softly. Baymax was humming melodically again.

He heard a whirr as Baymax loaded the supremely heavy-duty program he needed - probably the most complex thing Hiro had ever written, and yet something he would never ever share. The hum cut off, and the body underneath him froze for long minutes while Hiro snuggled his face into him, eventually reaching down to move the device away.

When Baymax woke up properly, eyes blinking, Hiro gave him a sleepy smile.

"We need to clean up, but I so don't want to get up."

"I will take care of you," said Baymax, scooping him up. Hiro squawked at him. He wasn't a kid anymore. But, Baymax supported him easily. "I would like to attempt a joke."

"Shoot," said Hiro, glad they had decided Baymax should warn him about incoming jokes.

"We would not want your platform to fall into disrepair, you only do have the one."

"Oh har-dee-ha, Baymax. Stick to your nursebot routine, you're never going to pull off the synthetic-over-organic supremacy shtick. Your face is too cute."

"I believe it is your face that is too cute," Baymax informed him, and carried him downstairs.

**Author's Note:**

> Title and some specific robot related terms taken from Mass Effect.


End file.
